Wireless Energy Transfer Possibility

Wireless energy transfer has been thought about for decades by scientists all over the world. There were many experiments done and some are successfully till some extent.

In 2007, US researchers have successfully tested an experimental system to deliver power to devices without the need for wires.

The experimental setup consisted of two 60cm (2ft) diameter copper coils, a transmitter attached to a power source and a receiver placed 2m (7ft) away and attached to a light bulb. WiTricity, as it is called, exploits simple physics and could be adapted to charge other devices such as laptops.

The bulb was even made to glow when obstructions such as wood, metal and electronic devices were placed between the two coils.

“There is nothing in this that would have prevented them inventing this 10 or even 20 years ago,” commented Professor Sir John Pendry of Imperial College London who has seen the experiments.

The system should not present any significant health risk to humans as the body has almost zero response to magnetic fields in terms of the amount of power it absorbs.

How Wireless Electricity Could Work:

Power from mains to antenna, which is made of copper

Antenna resonates at a frequency of about 10MHz, producing electromagnetic waves

Tails’ of energy from antenna ‘tunnel’ up to 2m (6.5ft)

Electricity picked up by laptop’s antenna, which must also be resonating at 10MHz. Energy used to re-charge device

Energy not transferred to laptop re-absorbed by source antenna. People/other objects not affected as not resonating at 10MHz

First Commercial Wireless Electricity Experiment in Japan:

Currntly Japanese scientists are set to test the largest wireless electricity transmission ever attempted in a Tesla like spectacle that is sure to capture a great amount of atention and spark strong interest and support for a technology that could change the World. The event is to take place at the Tokyo Tower, the largest man made structure in Japan, at 1100 feet tall.

The nighttime experiment is meant to Illuminate the top spire of the mammoth steel structure to demmonstrate the use of the first wireless electricity transfer system in the World. The test is designed to transfer about 1200 watts of power at a range of 100 feet and will be a first of its kind use of a system Japanese scientists are developing to transmit power at distances they hope could reach 300 feet using a science that is based on magnetically coupled resonance.

The market for wireless electricity transfer is enormous, the Japanese Government thinks the first application would be electric vehicle charging. Chargers would be embedded into parking spaces, the vehicles would automatically charge eliminating the hassle of constantly plugging in. The automobile would be virtually maintence free. And to promote this idea the Japanese government envisions thousands of free charging spaces located around Toyko.

A transformer is an example of wireless energy transfer, although it does not seem to be so, due to the close proximity of the primary and secondary coils. If the coils are moved further appart and have different cores, instead of a common core, you have wireless energy transfer, due to the inductiion effect. However, the important issue here is the efficiency with which energy is trnsferred. The farther apart the coils are from each other, the less the tranfer efficiency. If this figure can be improved to reach e.g. 70% or 80% then we could have a practical way to tranfer energy without wires over long distances. If efficiency is ignored (or not important), as is the case of supplying small appliances, wireless energy transfer can be a very practical way of supply. However, if you are to supply thousands of watts to a circuit, things look a lot more difficult.